It is then necessary to setup an Alias for Apache.
If you want horde only on single pages, that are created with ispc3:
Add the following line to ISPConfig->Sites->Web Domain->Options->Apache directives
If you want to access webmail on all pages add the following line to /etc/apache2/apache2.conf - Does is matter where the line is added in apache2.conf?
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Alias /horde3 /usr/share/horde3
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